Considering that MS Paint is possibly the slowest, clunkiest art program available, since it changes things almost pixel by pixel, that is amazing! It is time-lapse, right? So we really don't know how much actual time it took.
I restored several ancient, bent, rusted daguerreotype photos with MS Paint. It was a labor of love--unknown relatives with floor length dresses and all dressed in tafetta and lace and bustles, and fellas with 5 button coats and swords. It took FOREVER, but it was fun.